<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Hello World in Browser</title>
    <script>
        // 这段JavaScript代码将在页面加载时执行
        window.onload = function() {
            document.body.innerHTML = '<h1>Hello, World!</h1>';
        };
    </script>
</head>
<body>
    <!-- 页面加载时，这里的内容将被JavaScript代码替换 -->
</body>
</html>